package com.huwaiwai.array;

import java.util.AbstractSequentialList;
import java.util.Collection;
import java.util.Deque;
import java.util.Iterator;
import java.util.List;
import java.util.ListIterator;
import java.util.NoSuchElementException;

/**
 * Created by hww on 2018/1/7 下午11:18.
 */
public class MyLinkedList<E> extends AbstractSequentialList<E>
        implements List<E>, Deque<E>, Cloneable, java.io.Serializable{

    private static class Node<E> {
        E item;
        Node<E> next;
        Node<E> prev;

        Node(Node<E> prev, E element, Node<E> next) {
            this.item = element;
            this.next = next;
            this.prev = prev;
        }
    }

    /**
     * 大小
     */
    transient int size = 0;

    /**
     * 头结点
     */
    transient Node<E> first;

    /**
     * 尾结点
     */
    transient Node<E> last;

    /**
     * 默认构造器
     */
    public MyLinkedList() {}

    /**
     * 含参构造器
     * @param c
     */
    public MyLinkedList(Collection<? extends E> c) {
        this();
        addAll(c);
    }

    /**
     * 链接头结点
     * @param e
     */
    private void linkFirst(E e) {
        final Node<E> f = first;
        final Node<E> newNode = new Node<>(null, e, f);
        first = newNode;
        if (f == null) {
            last = newNode;
        } else {
            f.prev = newNode;
        }
        size++;
        modCount++;
    }

    /**
     * 链接尾结点
     * @param e
     */
    private void linkLast(E e) {
        final Node<E> l = last;
        final Node<E> newNode = new Node<>(l, e, null);
        last = newNode;
        if (l == null) {
            first = newNode;
        } else {
            l.next = newNode;
        }
        size++;
        modCount++;
    }

    /**
     * 向前链接元素
     * @param e
     * @param succ
     */
    void linkBefore(E e, Node<E> succ) {
        final Node<E> pred = succ.prev;
        final Node<E> newNode = new Node<>(pred, e, succ);
        succ.prev = newNode;
        if (pred == null) {
            first = newNode;
        } else {
            pred.next = newNode;
        }
        size++;
        modCount++;
    }

    /**
     * 移除头结点,并返回元素
     * @param f
     * @return
     */
    private E unlinkFirst(Node<E> f) {
        final E element = f.item;
        final Node<E> next = f.next;
        f.item = null;
        f.next = null;
        first = next;
        if (next == null) {
            last = null;
        } else {
            next.prev = null;
        }
        size--;
        modCount++;
        return element;
    }

    /**
     * 删除尾结点,并返回元素
     * @param l
     * @return
     */
    private E unlinkLast(Node<E> l) {
        final E element = l.item;
        final Node<E> prev = l.prev;
        l.item = null;
        l.prev = null;
        last = prev;
        if (prev == null) {
            first = null;
        } else {
            prev.next = null;
        }
        size--;
        modCount++;
        return element;
    }

    /**
     * 去掉某个元素
     * @param x
     * @return
     */
    E unlink(Node<E> x) {
        final E item = x.item;
        final Node<E> next = x.next;
        final Node<E> prev = x.prev;

        if (prev == null) {
            first = next;
        } else {
            prev.next = next;
            x.prev = null;
        }

        if (next == null) {
            last = prev;
        } else {
            next.prev = prev;
            x.next = null;
        }

        x.item = null;
        size--;
        modCount++;
        return item;
    }

    /**
     * 获取第一个元素
     * @return
     */
    public E getFirst() {
        final Node<E> f = first;
        if (f == null) {
            throw new NoSuchElementException();
        }
        return f.item;
    }

    /**
     * 获取最后一个元素
     * @return
     */
    public E getLast() {
        final Node<E> l = last;
        if (l == null) {
            throw new NoSuchElementException();
        }
        return l.item;
    }

    /**
     * 删除第一个元素
     * @return
     */
    public E removeFirst() {
        final Node<E> f = first;
        if (f == null)
            throw new NoSuchElementException();
        return unlinkFirst(f);
    }

    /**
     * 删除最后一个元素
     * @return
     */
    public E removeLast() {
        final Node<E> l = last;
        if (l == null)
            throw new NoSuchElementException();
        return unlinkLast(l);
    }

    /**
     * 添加第一元素
     * @param e
     */
    public void addFirst(E e) {
        linkFirst(e);
    }

    /**
     * 添加到最后
     * @param e
     */
    public void addLast(E e) {
        linkLast(e);
    }

    /**
     * 是否包含元素o
     * @param o
     * @return
     */
    public boolean contains(Object o) {
        return indexOf(o) != -1;
    }

    /**
     * 链表长度
     * @return
     */
    public int size() {
        return size;
    }

    /**
     * Returns an iterator over the elements in this deque in reverse
     * sequential order.  The elements will be returned in order from
     * last (tail) to first (head).
     *
     * @return an iterator over the elements in this deque in reverse
     * sequence
     */
    @Override
    public Iterator<E> descendingIterator() {
        return null;
    }

    /**
     * 添加一个元素
     * @param e
     * @return
     */
    public boolean add(E e) {
        linkLast(e);
        return true;
    }

    /**
     * 删除指定元素
     * @param o
     * @return
     */
    public boolean remove(Object o) {
        if (o == null) {
            for (Node<E> x = first; x != null; x = x.next) {
                if (x.item == null) {
                    unlink(x);
                    return true;
                }
            }
        } else {
            for (Node<E> x = first; x != null; x = x.next) {
                if (o.equals(x.item)) {
                    unlink(x);
                    return true;
                }
            }
        }
        return false;
    }

    public boolean addAll(Collection<? extends E> c) {
        return addAll(size, c);
    }

    public boolean addAll(int index, Collection<? extends E> c) {
        checkPositionIndex(index);

        Object[] a = c.toArray();
        int numNew = a.length;
        if (numNew == 0) {
            return false;
        }

        Node<E> pred, succ;
        if (index == size) {
            succ = null;
            pred = last;
        } else {
            succ = node(index);
            pred = succ.prev;
        }

        for (Object o : a) {
            E e = (E) o;
            Node<E> newNode = new Node<>(pred, e, null);
            if (pred == null) {
                first = newNode;
            } else {
                pred.next = newNode;
            }
            pred = newNode;
        }

        if (succ == null) {
            last = pred;
        } else {
            pred.next = succ;
            succ.prev = pred;
        }
        size += numNew;
        modCount++;
        return true;
    }

    /**
     * Returns a list iterator over the elements in this list (in proper
     * sequence).
     *
     * @param index index of first element to be returned from the list
     *              iterator (by a call to the <code>next</code> method)
     * @return a list iterator over the elements in this list (in proper
     * sequence)
     * @throws IndexOutOfBoundsException {@inheritDoc}
     */
    @Override
    public ListIterator<E> listIterator(int index) {
        return null;
    }

    public void clear() {
        for (Node<E> x = first; x != null;) {
            Node<E> next = x.next;
            x.item = null;
            x.next = null;
            x.prev = null;
            x = next;
        }
        first = last = null;
        size = 0;
        modCount++;
    }

    public E get(int index) {
        checkElementIndex(index);
        return node(index).item;
    }

    public E set(int index, E element) {
        checkElementIndex(index);
        Node<E> x = node(index);
        E oldVal = x.item;
        x.item = element;
        return oldVal;
    }

    public void add(int index, E element) {
        checkPositionIndex(index);

        if (index == size) {
            linkLast(element);
        } else {
            linkBefore(element, node(index));
        }
    }

    public E remove(int index) {
        checkElementIndex(index);
        return unlink(node(index));
    }

    private boolean isElementIndex(int index) {
        return index >= 0 && index < size;
    }

    private boolean isPositionIndex(int index) {
        return index >= 0 && index <= size;
    }

    private String outOfBoundsMsg(int index) {
        return "Index: "+index+", Size: "+size;
    }

    private void checkElementIndex(int index) {
        if (!isElementIndex(index))
            throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
    }

    private void checkPositionIndex(int index) {
        if (!isPositionIndex(index))
            throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
    }

    Node<E> node(int index) {
        if (index < (size >> 1)) {
            Node<E> x = first;
            for (int i = 0; i < index; i++) {
                x = x.next;
            }
            return x;
        } else {
            Node<E> x = last;
            for (int i = size - 1; i > index; i--) {
                x = x.prev;
            }
            return x;
        }
    }

    public int indexOf(Object o) {
        int index = 0;
        if (o == null) {
            for (Node<E> x = first; x != null; x = x.next) {
                if (x.item == null) {
                    return index;
                }
                index++;
            }
        } else {
            for (Node<E> x = last; x != null; x = x.prev) {
                if (o.equals(x.item)) {
                    return index;
                }
                index++;
            }
        }
        return -1;
    }

    public int lastIndexOf(Object o) {
        int index = size;
        if (o == null) {
            for (Node<E> x = last; x != null; x = x.prev) {
                index--;
                if (x.item == null)
                    return index;
            }
        } else {
            for (Node<E> x = last; x != null; x = x.prev) {
                index--;
                if (o.equals(x.item))
                    return index;
            }
        }
        return -1;
    }

    public E peek() {
        final Node<E> f = first;
        return (f == null) ? null : f.item;
    }

    public E element() {
        return getFirst();
    }

    public E poll() {
        final Node<E> f = first;
        return (f == null) ? null : unlinkFirst(f);
    }

    public E remove() {
        return removeFirst();
    }

    public boolean offer(E e) {
        return add(e);
    }

    public boolean offerFirst(E e) {
        addFirst(e);
        return true;
    }

    public boolean offerLast(E e) {
        addLast(e);
        return true;
    }

    public E peekFirst() {
        final Node<E> f = first;
        return (f == null) ? null : f.item;
    }

    public E peekLast() {
        final Node<E> l = last;
        return (l == null) ? null : l.item;
    }

    public E pollFirst() {
        final Node<E> f = first;
        return (f == null) ? null : unlinkFirst(f);
    }

    public E pollLast() {
        final Node<E> l = last;
        return (l == null) ? null : unlinkLast(l);
    }

    public void push(E e) {
        addFirst(e);
    }

    public E pop() {
        return removeFirst();
    }

    public boolean removeFirstOccurrence(Object o) {
        return remove(o);
    }

    /**
     * Removes the last occurrence of the specified element from this deque.
     * If the deque does not contain the element, it is unchanged.
     * More formally, removes the last element {@code e} such that
     * <tt>(o==null&nbsp;?&nbsp;e==null&nbsp;:&nbsp;o.equals(e))</tt>
     * (if such an element exists).
     * Returns {@code true} if this deque contained the specified element
     * (or equivalently, if this deque changed as a result of the call).
     *
     * @param o element to be removed from this deque, if present
     * @return {@code true} if an element was removed as a result of this call
     * @throws ClassCastException   if the class of the specified element
     *                              is incompatible with this deque
     *                              (<a href="Collection.html#optional-restrictions">optional</a>)
     * @throws NullPointerException if the specified element is null and this
     *                              deque does not permit null elements
     *                              (<a href="Collection.html#optional-restrictions">optional</a>)
     */
    @Override
    public boolean removeLastOccurrence(Object o) {
        return false;
    }


}
